Open-ended chain for a traveling chain transmission having reverse bend prevention

ABSTRACT

A torque transmission system for effecting a driving connection between laterally spaced driving and driven shafts. A first wheel is mounted on the driving shaft, and a second wheel is mounted on the driven shaft. Each of the wheels have substantially identical pitch diameters. An endless, flexible torque transmitter operatively connects the first and second wheels. A traveling insert band circumscribes and operatively engages one of the wheels at a time, and when the traveling insert band engages one of the wheels, the insert band is located radially inwardly of the endless flexible torque transmitter. The traveling insert band has leading and trailing ends located in substantially circumferentially opposed juxtaposition when the traveling insert band operatively engages one of the wheels. A mechanism is also provided selectively to derail the leading end of the traveling insert band from that wheel operatively engaged thereby and to limit the reverse radius of curvature that the traveling insert can achieve during transfer. The traveling insert band is adapted, when its leading end is derailed from one of the wheels to travel to the other of the wheels and to circumscribe and operatively engage the other wheel radially inwardly of the endless torque transmitter thereby providing a different speed ratio between said driving and driven shafts.

This is a Continuation-in-Part of application U.S. Ser. No. 07/808,246,filed Dec. 16, 1991, which is a Continuation-in-Part of U.S. Ser. No.07/786,148, filed Oct. 31, 1991.

TECHNICAL FIELD

The present invention relates generally to a novel and unique travelingchain transmission system. More particularly, the present inventionrelates to a torque transmission system utilizing an endless chain toeffect an operative drive between two torque transfer sprockets mounted,respectively, on laterally spaced, driving and driven shaft means.Specifically, the present invention relates to the use of an open-endedtraveling chain, having reverse bend protection, which is selectivelymovable between the two sprockets during operation of the transmission,to effect a predetermined change in the operative pitch diameters of thesprockets and thereby provide a two-speed drive ratio between thedriving and the driven shafts by selective placement of the travelingchain about one or the other of the sprockets.

BACKGROUND OF THE INVENTION

Torque transmission systems which interconnect a drive shaft to aparallel, driven shaft conventionally employ chain or belt torquetransfer systems which operatively connect the parallel shafts, each ofwhich has a sprocket or pulley of different pitch diameter to produce afixed-speed drive ratio therebetween. To provide even a two-speed driveratio between such shafts has historically required a rather complexarrangement of gears and torque transfer devices, the latter generallycomprising clutches and/or brakes. To change the speed of the driveratios with the prior known arrangements has required shift clutches andintermeshing gears with bearings and rotating components, each of whichcontribute to losses in overall efficiency.

Another somewhat less expensive but no less technically complexarrangement has employed multiple sprockets on each shaft. In thatarrangement, the sprockets on one shaft are each aligned with sprocketson the other shaft, and a chain drive selectively interconnects thealigned pairs of sprockets. A derailleur selectively transfersengagement of the chain drive between the aligned pairs of sprockets sothat the drive ratios can be selected between those provided by thepairs of aligned sprockets.

Because of the costs to manufacture and maintain, the prior artarrangements as well as the need to remove the load during the shift,many parallel shaft installations are simply provided with a fixed-speeddrive ratio. Such a fixed-speed drive ratio provides a weighted averageor compromise between the highest and lowest drive ratios desired for aparticular installation. In short, the prior known structuralarrangements which provide selective drive ratios are overlysophisticated and overly expensive to be employed in many torquetransmission systems for which they are desired, and for which theywould be beneficial, were it not for the overall costs and complexity ofthe structures heretofore available for providing selective driveratios.

SUMMARY OF THE INVENTION

It is, therefore, a primary object of the present invention to provide anovel and unique open-ended chain structure for a traveling chaintransmission system.

It is another object of the present invention to provide a novel reversebend structure for a traveling chain transmission system, as above, inwhich the traveling chain has interactive structures for limiting theradius of curvature in one direction.

It is a further object of the present invention to provide a novel chainstructure for a traveling transmission system, as above, which providesmeans for limiting the reverse bending of the traveling chain to apredetermined radius between the sprockets on which the chain isselectively wrapped.

These and other objects of the invention, as well as the advantagesthereof over existing and prior art forms, which will be apparent inview of the following detailed specification, are accomplished by meanshereinafter described and claimed.

In general, a traveling chain torque transmission system embodying theconcepts of the present invention is adapted to be operativelyinterconnected between a pair of laterally spaced parallel shafts.Sprockets are mounted on each shaft, and an endless flexible torquetransmitting chain mechanism operatively connects the two sprockets.

A traveling chain insert band means selectively circumscribes one or theother of the sprockets radially inwardly of the endless flexible torquetransmitting chain mechanism. The traveling chain has free leading andtrailing ends which are normally disposed in circumferential oppositionwhen the traveling insert band means circumscribes either of thesprockets. The traveling insert chain is adapted, when its leading endis disengaged, by way of a derailing and locking mechanism, from thesprocket on which the traveling chain is received, to travel to theother sprocket and progressively circumscribe that sprocket.

The derailing and locking mechanism prevents the traveling chain frominadvertently traveling between the sprockets. However, at the initialpoint of derailment it is possible for the chain links to assume areverse bend attitude that will interfere with the derailment. Thepresent chain structure provides a cooperating stop structure onadjacent chain components that limit the reverse bend radius of thechain. In the embodiment presented below, the stop structure iscomprised of an outwardly protruding shoulder on each load block and afinger portion extending longitudinally from each end of the sideplates. The fingers engage the shoulder at a predetermined angle tolimit the articulation of the adjacent chain components and thereby alsolimit the reverse radius of curvature of the traveling chain.

An exemplary embodiment of the present chain structure of the torquetransmission system is described herein, and this embodiment is deemedsufficient to effect a full disclosure of the subject invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevation of a torque transmission systemdepicting an insert band in the nature of a traveling chaincircumscribing a sprocket attached to the driving shaft to provide themaximum overdrive gear ratio, the traveling chain being depicted inchain line, as is the endless flexible torque transmitting means whichis operatively connected between the wheel means.

FIG. 2 is a schematic side elevation similar to FIG. 1, but depictingthe system in the derailing mode, which permits the leading end of thetraveling chain to disengage from the sprocket on the driving shaft, thetraveling chain now being depicted in side elevation but the endlessflexible torque transmitting means continues to be depicted in chainline.

FIG. 3 is a side elevation of a resilient disk which serves as a keyelement in the derailing and locking mechanism employed by the torquetransmission system depicted.

FIG. 4 is a vertical cross section taken substantially along line 4--4of FIG. 3.

FIG. 5 is a further schematic similar to FIG. 2, but depicting thecomponents in greater detail, both the traveling chain and the endlessflexible torque transmitting means in the nature of a chain beingdepicted in side elevation.

FIG. 6 is an enlarged vertical cross section taken substantially alongline 6--6 of FIG. 5 depicting the interaction of the resilient disk anda reaction pin in not only the retaining mode, but also the derailingmode, and the converse thereof, the insertion mode.

FIG. 7 is an enlarged area of FIG. 5 depicting the interaction of theleading end block with an ejector and an opposed tensioner at theinitiation of the derailing mode.

FIG. 8 is a perspective view of the mechanism depicted in side elevationin FIG. 7.

FIG. 9 is a perspective view similar to FIG. 8, but depicting theinsertion of the tongue on the leading end block between the sprocketand the endless drive chain.

FIG. 10 is a top plan view, of reduced size, of the mechanism depictedin FIG. 7, but showing the interaction of the shift actuator with theresilient disks of the containment means as the initiation of thederailing mode.

FIG. 11 is a side elevation of the mechanism depicted in FIG. 10.

FIG. 12 is an enlarged cross section taken substantially along line12--12 of FIG. 11.

FIG. 13 is a side elevation view of the traveling chain showing thechain in the limited reverse bend attitude.

FIG. 14 is a bottom view of the chain shown in FIG. 13.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

A traveling chain torque transmission system which embodies the conceptsof the present invention is identified in FIGS. 1 through 12 by thenumeral 211. The system 211 is employed to effect a driving connectionbetween two parallel shafts 213 and 215 which are identified as thedriving and the driven shafts, respectively. Each shaft 213 and 215 mayalso be mounted for rotation on a bearing assembly 217. Torque transferwheel means or sprockets are mounted on each of the shafts 213 and 215,and in the embodiment depicted in FIGS. 1-12, the wheel means maycomprise sprockets 219 and 221 which are operatively secured to therespective shafts 213 and 215.

In the embodiment described, the sprockets also have the same pitchdiameter 235 and are connected by an endless, flexible torquetransmitting means 223 (FIG. 5) which may be a conventional silent drivechain which meshes with the teeth 233 on each sprocket 219 and 221. Thatis, and as best seen in FIGS. 5 and 9, the endless drive chain 223 maybe comprised of a plurality of toothed links 225 conjoined by connectinglinks 227 and connecting pins 229. In order to minimize the complexityof the drawings, only two representative connecting links 227 aredepicted in FIG. 5.

It should also be understood that the toothed links 225 may be fashionedfrom solid blocks attached by a pair of external connecting links (notshown), or as shown, the drive chain 223 may comprise stacked toothedand connecting links, as is customarily employed in the typical silentchain configuration. In either arrangement, each toothed link 225presents a pair of teeth 231 which have a pitch dimension determined bythe length of the toothed links 225 taken in conjunction with the lengthof the connecting links 227 so that the teeth 231 will mesh with theteeth 233 on each sprocket 219 and 221.

A traveling chain 237 (FIG. 2) is comprised of a plurality of uniqueinsert load transfer blocks or chain links 239 which cooperativelyinteract with the teeth 233 on each sprocket 219 and 221, as well aswith the teeth 231 (FIG. 5) on the endless drive chain 223. Thethickness of the load transfer blocks 239 increases the effective pitchdiameter from that which is designated by the numeral 235 in FIG. 1 tothat which is designated by the numeral 249 in FIG. 2 of whicheversprocket 219 or 221 is circumscribed by the traveling chain 237--thethickness of the load transfer blocks 239 being measured radially withrespect to the sprocket about which the traveling chain 237 iscircumscribed. Each transfer block 239 has a pair of axially extendingprotuberances or shoulders 240.

The successive insert load transfer blocks 239 are conjoined byconnector links or side plates 241, laterally spaced pairs of whichembrace a portion of the lateral sides on two successive blocks and arepivotally attached to each block by pins 243. It will be observed thatonly one of the connector links 241 is depicted in FIG. 2 in order tominimize the clutter that would result if all the connector links 241were included on that figure. Each connector link 241 has a finger 242extending longitudinally from each end. The fingers 242 are disposed inclose proximity for interaction with respective shoulders 240 of theblocks 239 which shoulders 240 are situated between the fingers ofadjacent connector links 241.

It must be understood that, in the torque transmission system 211, thepins 243 serve a dual purpose in that they not only effect a pivotalconnection between each transfer block 239 and the connector links 241by which the load transfer blocks 239 are joined, but they are alsoutilized to effect the blocking and derailing modes, as will behereinafter more fully explained.

As may most clearly be seen in FIG. 2, a pair of radially inwardlydirected teeth 245 are presented from each load transfer block 239. Thepitch dimension "P" for the teeth 245 must be equal to the pitchdimension "P" for the teeth 233 on each of the sprockets 219 and 221 toeffect meshing engagement between each load transfer block 239 andeither sprocket 219 or 221. As such, the length of the connector links241 will be selected to permit the desired articulation betweensuccessive load transfer blocks 239 and also to assure that thesuccessive load transfer blocks 239 mesh with the sprockets 219 and 221.

Continued reference to FIG. 2 reveals that each load transfer block 239also presents a pair of outwardly directed cogs 247. The pitch dimension"P" between the successive cogs 247 on each insert load transfer block239 is selected to be exactly equal to the pitch dimension "P" betweenthe teeth 233 on each sprocket 219 and 221. As such, the cogs 247 oneach insert load transfer block 239 will meshingly engage with the teeth231 on the endless drive chain 223 as represented in FIG. 5.

However, it should be appreciated that when the traveling chain 237 isinserted between either sprocket 219 or 221 and the endless drive chain223, that sprocket 219 or 221 will thereby have an increased effectivepitch diameter 249 (FIG. 2). The increase in the pitch diameter isproportional to the thickness of the traveling chain 237. To accommodatefor this difference in the effective pitch diameters 235 and 249 of thesprockets when the traveling chain 237 is circumscribed in whole or inpart about one of the sprockets 219 or 221, the thickness of thetraveling chain 237 may be judiciously selected such that the insertblocks 239 may effectively utilize nonsymmetrical placement of the cogs247 to effect a nonbinding, torque transfer between the traveling chain237 and the drive chain 223.

As best shown in FIG. 5, the nonsymmetrical placement of the cogs 247,if the dimensions are properly selected, permits successive insert loadtransfer blocks 239 to be reversed such that the successive insert loadtransfer present mirror images of each other. This arrangement allowsall insert load transfer blocks 239 to be identical. As such, when thetraveling chain 237 is interposed between either sprocket 219 or 221 andthe endless drive chain 223, every fourth and fifth tooth 231 on theendless drive chain 223 will only be engaged by one cog 247, also asshown in FIG. 14.

In other words, because the cogs 247 mesh with the teeth 231 on thedrive chain 223, the pitch dimension for the cogs 247 must also equaldimension "P". To provide the same pitch dimension on both sides of thetraveling chain 237 the load transfer blocks 239 have an asymmetricaldesign; viz., the two cogs 247 on each load transfer block 239 areoffset with respect to the center of each block 239. As such, when thetraveling chain 237 circumscribes either sprocket 219 or 221, afictitious cog wheel is presented wherein a cog is missing atpredetermined circumferential locations.

As best seen in FIGS. 5, 8 and 9, the traveling chain 237 also has aleading end block 251, which presents a tongue 253, and a trailing endblock 255 (FIG. 5), which also presents a tongue 253. The leading andtrailing end blocks 251 and 255 may also be identical. Hence, when theblocks 251 and 255 are disposed at opposite ends of the traveling chain237 and are disposed in circumferential opposition, the tongues 253 onthe leading and trailing end blocks 251 and 255 lie in adjacentjuxtaposition. Each block 251 also has a nose portion 254 protrudingfrom the outer edge thereof and extending in the direction of the tongue253. As will become apparent, the tongues 253 and noses 254 provide asmooth penetration of the traveling chain 237 to a position where it isinterposed between the drive chain 223 and either sprocket 219 or 221,as well as a smooth exit as the traveling chain 237 leaves one sprocketfor the other. The smooth penetration so provided assures a positivesynchronous engagement of the traveling chain 237 with not only thedrive chain 223 but also the sprockets 219 or 221.

In order to maintain the traveling chain 237 in operative, peripheralengagement with the sprocket 219 or 221, a containment means 257 (FIG.6) is provided. The containment means 257 must act in concert with theinsert load transfer blocks 239 and/or the reaction pins 243 presentedfrom the traveling chain 237 to maintain the traveling chain 237 inoperative engagement with whichever of the sprockets 219 or 221 aboutwhich it is received. An ejection means, as hereinafter more fullydescribed, may be employed in association with the containment means 257effectively to direct the leading end block 251 outwardly and away fromthe sprocket about which the traveling chain 237 is circumscribed.

The containment means 257 utilized with the torque transfer system 211,depicted in FIGS. 1 through 12, incorporates a resilient disk 259 (FIGS.3 and 4) that is secured to at least one side of each sprocket 219 and221. As shown, however, both sprockets 219 and 221 are embraced betweenresilient disks 259 in the nature of Belleville springs that are securedto opposite sides of each sprocket 219 and 221.

FIG. 3 is an elevational view of one of the resilient disks 259. Eachresilient disk 259 has a series of circumferentially spaced generallyradially extending offset slots 261. Portion 261A of each slot 261emanates from the generally planar central body portion 259A and extendsradially outwardly to define a pie-shaped segment 259B between theportion 261A of each slot 261. Each portion 261b is inclined from aradial reference at a projected angle beta (FIG. 3) and each portion261b extends between the circumferentially successive cam followerportions 259C. The cam follower portions 259C are inclined laterallywith respect to the central body portions 259a and the coplanar segments259B, as is best represented in FIG. 4.

The radially outermost extent of each cam follower portion 259C joins alaterally oriented extender portion 259D and the adjacent extenderportions 259D are separated by portion 261C of the slot 261. Theextender portions 259D compositely form a discontinuous annulus which isinterrupted by the circumferentially spaced portions 261C of slot 261.Each portion 261C may lie within a radial plane which includes therotational axis 265 of the disk 259. An end portion 259E extendsradially outwardly from each extender portion 259D, and as such, the endportions 259E may lie in a plane that is substantially parallel to, butlaterally offset from, the planar central portion 259A and the segments259B. The outer end portions 259E are separated by a radially extendingportion 261D of the slot 261.

A series of engaging apertures 267 are disposed in a circulardisposition concentrically about the rotational axis 265 of theresilient disk, which is coincident with the rotational axis of eachsprocket 219 and 221, and the apertures 267 are circumferentially spacedsuch that one aperture 267 is located in each segment 259B. Theapertures 267 in the resilient disks 259 cooperate with the reactionpins 243 to serve as the containment means 257 and to retain thetraveling chain 237 on one or the other of the sprockets 219 or 221. Aswill become apparent, the inclined portions 261b of the offset slot 261are provided and oriented to prevent the reaction pins 243 from havingto cross any of the slots 261, particularly as the ends of the pins 243engage and slide along the cam follower 259C and the segment 259B of theresilient disk 259 during the process of moving to engage the apertures267.

Referring again to FIG. 1, guide means 271 are employed to direct thetraveling chain 237 between the laterally spaced sprockets 219 and 221.The guide means 271 employs a central frame block 273 that may besupported in any manner convenient to the environment in which thesystem 211 is employed. The lateral sides of the central frame block 273presents tracks or guide rails 275 which are raised above and extendlaterally along the recessed upper and lower surfaces 277A and 277B ofthe block 273, and which extend arcuately between the sprockets 219 and221.

As is depicted in FIGS. 1 and 8, the central frame block 273 presentscurved tracks 275A and 275B which are raised above and extend along therecessed upper surface 277A. Likewise, curved tracks 275C and 275D areraised above and extend along the recessed lower surface 277B. As such,the tracks 275 extend between the sprockets 219 and 221 to define theruns of the traveling chain 237. The opposite ends of each track 275present ingress and egress spans 279 and 281 (FIG. 1) which are open,and communicate with, the paths along which the traveling chain 237 willmove during a shift, as will be hereinafter more fully described.

It should be understood that when the interaction between the travelingchain 237 and the sprockets 219 and 221 is accomplished by teeth 245, asis the situation in torque transfer system 211, the tracks 275 must bearcuate to direct the traveling chain 237 away from the endless drivechain 223 during the movement of the traveling chain 237 as it transfersbetween the sprockets 219 and 221. In that regard, it has been foundthat the arc of each track 275 should preferably be tangent to the pitchcircle 283 of each sprocket 219 or 221. Penetration of the travelingchain 237 along that tangent assists in the facile operation of thetransmission system 211, as will also be hereinafter more fullyexplained.

Tensioners 285 are mounted in opposition to each track 275. Eachtensioner 285 has an arcuate engaging surface 287 disposed in oppositionto one of the tracks 275. Each tensioner 285 is pivotally mounted, as bya pivot pin 289, and is biased, as by the compression spring 291, suchthat the arcuate engaging surface 289 is biased toward but in generallyspaced relation with respect to, the opposed track 275.

Ejectors 293 may also be employed. When provided, each ejector 293 willbe received in a recess 295 formed adjacent and along the outside ofeach track 275 in proximity to the egress span 281. Each ejector 293will have a directing surface or guide track 297 which terminates in anapex 299. The apex 299 is disposed in close proximity to and radiallyoutwardly from the traveling chain 237 as that chain circumscribeseither sprocket 219 or 221 while being retained thereon by thecontainment means 257; i.e., as shown at the interaction between theresilient disk 259 and the reaction pins 243. A coil spring 301 normallybiases the ejector 293 such that the directing surface 297 is normallydisposed to lie along the adjacent track 275. The apex 299 and directingsurface 297 cooperate with the nose 254 of block 251 to assist inseparation of the traveling chain 237 from the sprocket, if necessary,since, at times, the friction forces between the teeth 233, 245 may bequite high relative to the centripetal force.

However, in response to the application of any force to the apex 299 orthe directing surface 297, the ejector 293 will pivot against thebiasing action of the coil spring 301 to swing toward the adjacentsprocket 219 or 221 for a purpose that will shortly become apparent.

A shift actuator 303, which is detailed in FIGS. 9-11 and which isassociated with each sprocket 219 and 221, has a pair of spring biasedshoes 305 which may be in the general configuration of quadrant platesthat selectively translate laterally (as represented in FIG. 6) toengage the radially outer end portions 259e of the resilient disks 259associated with the sprocket about which the traveling chain 237 iscircumscribed. The shoes 305 are biased by a compression spring 317which acts upon a biasing shaft 319 that coacts with the mounting arms321A and 321B for the respective shoes 305A and 305B. The compressionspring 317 thus acts to maintain the shoes 305A and 305B out ofengagement with the resilient disk 259, as best seen in FIGS. 9 and 12.However, the shoes 305 may, as shown, be translated against the biasingaction of spring 317 by operation of a fluid cylinder 307 whichreciprocates a conical head 309 that engages the inboard end 311 of eachactuating pin 313 which is also presented from the mounting arms 321.

To shift into the maximum underdrive ratio, the fluid cylinder 307 isactuated to drive the conical head 309 outwardly into engagement withthe inboard ends 311 of the support pins 313, thus driving the pins 313apart and thereby forcing the bulbous camming surfaces 315A and 315Bpresented from the shoes 305A and 305B into engagement with the outerend portions 259e of the resilient disks 259A and 259B secured to thesprocket 219. This movement causes those segments 259b which aredirectly connected to the outer end portions 259e that are engaged bythe camming surface 315 on the shoes 305 to flex laterally apart, asshown in FIG. 6, and thereby release the reaction pins 243 from theapertures 267 within which they are received.

When the reaction pin 243A, presented from the leading end block 251 ofthe traveling chain 237 is thus released, centrifugal force will tend tothrow the tongue 253 on the leading end block 251 radially outwardly.Radial displacement of the tongue 253 on the leading end block 251 willcause the reaction pin 342A, following the nose 254, to engage the apex299, and sequentially thereafter the directing surface 297 on theejector 293 (FIG. 1), such that the traveling chain 237 will passthrough the egress span 281B to engage, and move along, the track 275A.

To ensure that the traveling chain 237 exits the sprocket 219 or 221 asdesired, the fingers 242 cooperate and interact with the respectiveprotuberances 240 thereby limiting the reverse bend or reverse radius ofcurvature of the traveling chain 237, as shown in FIG. 13. Thus, thetransient friction forces between the teeth on the sprocket and chainare overcome, when necessary, by the abutment of the fingers 242 withthe protuberances 240. Preferably, the traveling chain 237 is designedto have a maximum reverse radius of curvature equal to or slightly lessthan the radius of curvature of the track 275. The interaction betweenthe fingers 242 and protuberances 240 will prevent the load blocks 243from remaining in engagement with the sprocket 219 or 221 rather thanfollow the lead block 251 along the track 275.

It will be noted that the torque transfer system 211 may satisfactorilyoperate without the use of an ejector 293. However, in order to becertain of derailment at the slowest rotational speed of the sprocketupon which the traveling chain 237 is circumscribed, an ejector 293 maybe employed to translate the slightest displacement of the tongue 253,and thus the reaction pin 243A, on the leading end block 251 into thedesired initiation of a shift.

Irrespective of whether or not an ejector 293 is employed, once theleading end block 251 passes through the egress span 281B, cooperationbetween protuberances 240 and fingers 242 will force the remainingportion of the traveling chain 237 on the sprocket 219 to eject alongthe tracks 275A and 275B until the trailing end block 255 of thetraveling chain 237 is released. The lineal length of the travelingchain 237 is such that when the trailing end block 255 leaves sprocket219, the leading end block 251 will already have passed through theingress span 279A to engage the teeth 233 on the sprocket 221.

Because the total length of the traveling chain 237 is fixed, as ageneral rule the length of the tracks 275 are approximately one-half thecircumference of either sprocket 219 or 221. The center distance betweensprockets, as well as the pitch radii of the those sprockets, areconcomitantly selected to assure that during a shift the traveling chain237 will have engaged one sprocket before having totally disengaged fromthe other sprocket, and more importantly, to assure that the endlesschain 223 is neither slackened nor overtightened during the shift.

Referring to FIG. 9, when the tongue 253 on the leading end block 251 ofthe traveling chain 237 is positioned to wedge between the teeth 233 ofsprocket 221 and the teeth 231 of the drive chain 223, The reaction pin243A projecting from one side of the tongue 253 on the leading end block251 will engage the respective inclined cam follower 259c of therespective disk segment 259b happens to be aligned with the ingress span279.

As the leading end block 251 is captured between the endless drive chain223 and the sprocket 221, the reaction pin 243A, and the successivereaction pins 243, will each engage successive cam followers 259c in theresilient disk 259. Such captured engagement, coupled with the continuedrotation of the sprocket 221, will flex the segments 259b directlyconnected to the cam followers 259c until the initial, and successive,reaction pins 243 enter the appropriate apertures 267. This entry allowsthe disk segments 259b to spring back to their normal position,whereupon the traveling chain 237 will begin to circumscribe and becontained on the sprocket 221.

It should be noted that by employing the canted portion 261b of the slot261, none of the reaction pins 243 will attempt to enter any slot 261,but rather each reaction pin 243 will slide along one cam follower 259c,and the segment 259b directly associated therewith, until eachsuccessive reaction pin 243 aligns with and enters an aperture 267.

A kinematic study will reveal that there is a change in the length ofthe path of the traveling chain 237 during the transition from onesprocket to the other. The tensioners 285 are provided to absorb thisdynamic change in the length of the path of the traveling chain 237during the transition from one sprocket to the other. Thus, at themoment, when the length of the traveling chain path is shortened, asresults when the traveling chain 237 begins to circumscribe itself aboutthe sprocket which is rotating at a higher rotational velocity, as doesthe sprocket on the driven shaft in the overdrive situation, thetensioners 285 will move outwardly away from the tracks 275 to effect anaccommodation for the apparent, momentary change in the length of thetraveling chain path during the shift.

With the traveling chain 237 having been moved from sprocket 219 tosprocket 221, a shift from the maximum underdrive to the maximumoverdrive ratio will have been accomplished. In order to provide propermating of the traveling chain 237 with the teeth 233 of sprocket 219 or221, the leading end block 251, and the tongue 253 presented therefrom,must approach the pitch circle 283 of each sprocket 219 or 221tangentially. This is accomplished by the angular disposition of thearcuate track 275 as it terminates in tangential alignment with thepitch circle 283.

As best seen in FIG. 13, each protuberance 240 is essentially pentagonalin cross section having three slightly curved side surfaces 350, 351,352 which accommodate the tooth profile in the load block 239 and thecurved ends of the connecting links 241 and a pair of flat surfaces 354,355 which cooperate with flat surfaces 357, 359 formed on the fingers242A and 242B to limit the articulation of the load blocks 239 relativeto the connecting links 241 and thereby limit the reverse radius ofcurvature of the traveling chain 237 as it egresses from the sprocketinto the guide track 275. It can be appreciated by viewing FIG. 2, ifthe connecting links 241 and load blocks 239 are permitted unrestrictedarticulation, the leading block 251 can be directed to egress thesprocket 219 while the next, or any, load block 239 could remain in meshwith the sprocket and not be directed into the guide track 275. thiswould prevent continued operation of the traveling chain. It is possiblefor this to occur at low rotary speeds when the frictional forces aregreater than the centrifugal forces. This condition is prevented by thereverse bend restriction imposed by the finger 242 interacting with theprotuberances 240.

To ensure that the load transfer block 239 and connecting link 241follow the lead block 251 into the guide track 275, a pair of elongatedprotuberances 360 extend along the lead block 251 from the nose 254. Aflat surface 361, formed on each protuberance 360, cooperates with theflat surface 355A to restrict the articulation therebetween. Since thetrailing block 255 is identical with the leading block 251, an identicalstructure is incorporated therein which will ensure the properdisposition of the trailing block 255.

As best seen in FIG. 14, the leading block 251 and trailing block 255are merely turned end for end at assembly such that, when the travelingchain 237 encircles one of the sprockets 219 or 221 the tongues 253A,253B of the leading block 251 will be inserted in respective slots 363,365 which are formed in the trailing block 255. Likewise, the tongues253 of the trailing block 255 will interdigitate with the slots 363, 365of the leading block 251.

When it is desired to shift speeds and return the traveling chain 237 tothe sprocket 219, the shifting operation is reversed, but that shift isaccomplished in the same manner heretofore described.

The configuration of the traveling chain 237 in the torque transmissionsystem 211 and its interaction with the drive chain 223 and thesprockets 219 and 221 not only has the advantage of providing a soliddesign with noise reduction but also an automatic derailing system thateliminates the need for gates.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A torque transmissionsystem for operatively connecting laterally spaced driving and drivenshaft means, said system comprising:a sprocket mounted on each saidshaft; each said sprocket having radially extending teeth located alongthe circumference thereof; an endless flexible chain which cooperativelyinteracts with said teeth on said sprockets; a traveling chain adaptedcooperatively to interact with said teeth on either of said sprocketsand having cogs which cooperatively interact with the endless flexiblechain along that portion of said traveling chain which engages the teethon either said sprocket; and means being provided for selectivelydisengaging the leading end of said traveling chain from whichever ofsaid sprockets is circumscribed by said traveling chain during drivingmovement of said endless chain and for guiding the traveling chain fromone sprocket to the other sprocket, said traveling chain having aleading end, a trailing end, a plurality of load blocks and a pluralityof side plates which define the length of said traveling chain, and pinmeans interconnecting respective side plates with respective load blocksand the leading and trailing ends such that the traveling chain willsubstantially circumscribe either of said sprockets, said load blocksand said side plates having interactive means for limiting the travelingchain to a predetermined reverse radius of curvature when the chain istraveling from one sprocket to the other sprocket.
 2. A torquetransmission system for operatively connecting laterally spaced drivingand driven shaft means, said system comprising:a sprocket mounted oneach said shaft; each said sprocket having radially extending teethlocated along the circumference thereof; an endless flexible chain whichcooperatively interacts with said teeth on said sprockets; a travelingchain adapted cooperatively to interact with said teeth on either ofsaid sprockets and having cogs which cooperatively interact with theendless flexible chain along that portion of said traveling chain whichengages the teeth on either said sprocket; said traveling chain having aleading end, a trailing end, a plurality of load blocks and a pluralityof side plates which define the length of said traveling chain, and pinmeans interconnecting respective side plates with respective load blocksand the leading and trailing ends such that the traveling chain willsubstantially circumscribe either of said sprockets, said load blocksand said side plates having interactive means including protuberances onsaid load blocks and said leading and trailing ends for limiting thetraveling chain to a predetermined reverse radius of curvature when thechain is traveling from one sprocket to the other sprocket; means beingprovided for selectively disengaging the leading end of said travelingchain from whichever of said sprockets is circumscribed by saidtraveling chain during driving movement of said endless chain; trackmeans to direct said traveling chain toward either of said sprocketswhen said traveling chain has been derailed from other of saidsprockets; and tongue means on at least the leading end of saidtraveling chain to facilitate meshing engagement between the cogs onsaid traveling chain and said endless chain as well as the teeth oneither of said sprockets.